Archer notes the tension in their hands. How they grip the knife. Inner conflict of some sort. Little nuances in which he takes in. His hands lift upward, his palms visible, to show that he had no weapons on his own being. At least, not in the phyiscal realm.

"I do not intend to fight with just anyone." He tries to reassure them. They didn't pose a threat to him. They never made that choice to actually lunge out at him when they had their knife drawn. Probably a safe move for the both of them. He lowers his hands.

"I'm summoned to fight for others." Archer wasn't some blood thirsty fighter who looked around every corner to find a willing opponent. His main targets were other Servants like himself, and other Masters. Then again, there was the possibility of others looking for fights here. And Archer would rise to occasion, if that were the case.